Electronic devices such as laptop PCs, tablet PCs, digital cameras, and mobile phones, which are portable while being used by the user are rapidly increasing in recent years. Many of these electronic devices have therein a rechargeable battery, which requires periodical charging. To facilitate the work for charging the rechargeable battery of an electronic device, there are an increasing number of devices for charging rechargeable batteries by using a power-supplying technology (wireless power transmission technology performing power transmission by varying the magnetic field) that performs wireless power transmission between a power-supplying device and a power-receiving device mounted in an electronic device.
Examples of such a wireless power transmission technology includes: a technology that performs power transmission by means of electromagnetic induction between coils (e.g. see PTL 1) and a technology that performs power transmission by means of resonance phenomena between resonators (coils) provided to the power-supplying device and the power-receiving device (e.g. see PTL 2).
Meanwhile, there is a demand for further downsizing (more compact structures for) the electronic devices such as laptop PCs, tablet PCs, digital cameras, and mobile phones, which are portable while being used by the user, in order to improve the portability.
To achieve more compact electronic devices, while adopting a wireless power transmission technology, a conceivable approach is to accommodate a charge-related electronic component such as a rectifier and a rechargeable battery on an inner circumference side (inside) of the coil used for the wireless power transmission technology.
In the wireless power transmission technology however, a magnetic field occurs around the coil used. The occurrence of the magnetic field leads to an eddy current at the charge-related electronic component such as the rectifier, and the rechargeable battery accommodated on the inner circumference side (inside) of the coil, which generates heat and gives negative influence to the charge-related electronic component.
To address this issue, for example, PTL 3 discloses a power-receiving device having a rechargeable battery (secondary battery), in which influence of the magnetic flux is reduced with a magnetic foil member arranged between a spiral coil and a rectifier of the power-receiving device.